jaldis

Didn't spend a penny on EngineerPro's course. Worshipped the almighty camel 🐫 instead.

jaldis is a Redis-compatible key-value store implemented in OCaml.

Demonstration video: https://www.youtube.com/watch?v=M3a44Lh2qUo

Benchmarking

Performance benchmarks using redis-benchmark against jaldis server (in Release mode):

Test Configuration

• Hardware: Intel Core i5-1135G7
• OS: Linux 6.18.7-arch1-1
• OCaml: 5.3.0
• Network: localhost
• Test Parameters: 1,000,000 SET/GET operations, 100 concurrent connections

# Standard benchmark
redis-benchmark -h 127.0.0.1 -p 6969 -n 1000000 -c 100 -t set,get --csv

# Pipelined benchmark (16 commands per pipeline)
redis-benchmark -h 127.0.0.1 -p 6969 -n 1000000 -c 100 -t set,get -P 16 --csv

Results

Standard Mode (-P 1)

"test","rps","avg_latency_ms","min_latency_ms","p50_latency_ms","p95_latency_ms","p99_latency_ms","max_latency_ms"
"SET","108026.36","0.851","0.224","0.879","1.247","1.551","14.343"
"GET","107411.38","0.853","0.216","0.879","1.295","1.655","13.455"

Pipelined Mode (-P 16)

"test","rps","avg_latency_ms","min_latency_ms","p50_latency_ms","p95_latency_ms","p99_latency_ms","max_latency_ms"
"SET","244977.97","6.393","1.848","6.327","7.711","9.055","21.519"
"GET","296033.16","5.254","1.256","5.183","6.591","7.831","19.903"

Features

Data Types

• Strings - Store and retrieve text values
• Lists - Ordered collections with push/pop operations
• Sets - Unordered collections of unique elements

Core Operations

• SET/GET - Basic key-value operations
• DEL - Delete keys
• KEYS - List all keys
• FLUSHDB - Clear all data

List Operations

• LPUSH/RPUSH - Push elements to front/back
• LPOP/RPOP - Pop elements from front/back (with optional count)
• LLEN - Get list length
• LRANGE - Get elements in range

Set Operations

• SADD - Add elements to set
• SREM - Remove elements from set
• SCARD - Get set size
• SMEMBERS - Get all set members
• SINTER - Set intersection
• SISMEMBER - Check membership

Expiration & TTL

• EXPIRE - Set key expiration in seconds
• TTL - Get time-to-live for key
• Automatic cleanup - Background sweep removes expired keys

Protocol Support

• RESP (Redis Serialization Protocol) - Full compatibility with Redis clients
• TCP server - Standard Redis port (6379) or custom port

Installation

Prerequisites

• OCaml 5.0+
• Dune 3.17+
• OPAM package manager

Dependencies

opam install core async ppx_jane zarith angstrom angstrom-async

Build

git clone https://github.com/jalsol/jaldis.git
cd jaldis
dune build
dune build --release # Release mode

Usage

Start Server

# Default port 6969
dune exec server

# Custom port
dune exec server -- -port 6379

Architecture

Core Components

• Storage Engine - In-memory hash tables with expiration tracking
• RESP Parser - Full Redis protocol implementation
• Command Handler - Redis-compatible command processing
• Async Server - High-performance TCP server using Jane Street's Async

Performance Features

• Optimized Expiration - Hybrid sweep strategy (O(1) for large datasets)
• Memory Efficient - Separate storage and expiration tracking
• Non-blocking - Asynchronous I/O for concurrent connections

Key Optimizations

• Small Tables (≤100 keys): Full scan with early termination
• Large Tables (>100 keys): Probabilistic sampling to avoid O(n) scans
• Background Cleanup - Automatic expired key removal every 100ms

Development

Run Tests

dune test

Format Code

dune fmt

Project Structure

jaldis/
├── bin/           # Server executable
├── misc/          # Utilities and test scripts
├── resp/          # RESP protocol implementation
├── server/        # Core storage and command handling
└── test/          # Unit and integration tests

Key Modules

• Storage - Core key-value storage with TTL support
• Commands - Redis command implementations
• Parser/Serializer - RESP protocol handling
• Rstring/Rlist/Rset - Data type specific operations

Compatibility

Redis Features Supported

• ✅ Core data types (String, List, Set)
• ✅ Expiration and TTL
• ✅ RESP protocol
• ✅ Most common commands
• ✅ Redis client compatibility

Not Yet Implemented

• Hash data type
• Sorted sets
• Pub/Sub
• Persistence
• Clustering
• Transactions

License

MIT License - see LICENSE file for details.